Hollow glassware can be made in a machine of the so-called I.S. type by extruding or otherwise inserting a gob of liquid glass into a preform where it is normally blown or pressed into a parison of concave shape. This parison is then transferred to a final mold where it is blow-molded, either by subjecting the parison internally to a superatmospheric pressure or externally to a subatmospheric pressure, into a finished article having the desired ultimate shape. Normally tongs or a neck ring transfer the parison from the preform to the final mold, and the same or another set of tongs or neck ring can be used to remove it from the final mold once the molding operation is complete.
In copending application Ser. No. 096,744 filed Nov. 23, 1979 (now U.S. Pat. No. 4,298,371) a method and apparatus are described wherein the parison is allowed to reside for a period sufficient to equalize its temperature before being blown into its ultimate shape. As the temperature of this parison equalizes and it is blown another final mold receives a parison that is meanwhile formed in the same premold. The two or more final molds associated with a given premold are mounted on a turntable for juxtaposition at a transfer position with the premold preparatory to each transfer step.
In this turntable system a so-called mold head is engaged with the top of the parison for closing it off and normally injecting pressurized air into the parison so as to press it against the inner walls of the final molds. Normally this mold head is provided at a fixed station adjacent the takeout station, so that the parison must be swung around to the takeout station before the mold head can be engaged with it and the blow-molding operation, which may employ either super- or subatmospheric pressure as mentioned above, can be carried out. As a result the system is somewhat slow in operation.